| Message ID | 20240109120738.346061-5-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kbuild: create a list of DTBs and allow to install base dtb and overlays | expand |
On Tue, Jan 09, 2024 at 09:07:37PM +0900, Masahiro Yamada wrote: > Commit 15d16d6dadf6 ("kbuild: Add generic rule to apply fdtoverlay") > introduced the -dtbs syntax to apply overlays during the build process. > > However, scripts/Makefile.dtbinst is not aware of the -dtbs syntax, > so 'make dtbs_install' installs the files directly added to dtb-y. > (Presumably, it was intentional.) Yes. The intent was the Makefile should define what's installed or not. There's 2 reasons to apply overlays in the build. The first is so a DTB can be refactored into a base plus overlay(s) and we keep the original full DTB. The second is to test that overlays actually apply because testing that at boot time in bootloader is a poor experience and we don't want overlays which don't apply to upstream DTs. Whatever targets you want installed put in dtb-y. Whatever targets are just for testing, put in dtb-. The latter are then enabled with CONFIG_OF_ALL_DTBS. > For example, consider this case: > > foo1-dtbs := foo_base.dtb foo_overlay1.dtbo > foo2-dtbs := foo_base.dtb foo_overlay2.dtbo > dtb-y := foo1.dtb foo2.dtb > > 'make dtbs_install' only installs foo1.dtb and foo2.dtb. It is suitable > when the boot image supports a single hardware configuration, or when > the boot loader in use does not support applying overlays. > > However, when creating a boot image with multiple board supports, it > wastes storage space, as foo1.dtb and foo2.dtb have foo_base.dtb in > common. > > From a space perspective, a more optimal solution is to install > foo_base.dtb, foo_overlay1.dtbo, and foo_overlay2.dtbo, then assemble > the final dtb (either foo1.dtb or foo2.dtb) on the boot loader. > > This commit adds a new flag, INSTALL_DTBS_PRIMITIVE. > > With INSTALL_DTBS_PRIMITIVE=1, 'make dtbs_install' will install primitive > files (such as foo_base.dtb, foo_overlay1.dtbo, and foo_overlay2.dtbo in > this case). And not install foo1.dtb and foo2.dtb, right? What if one wants to install everything? Seems like this needs to be a 3-way option. I'm not really convinced we need this in the first place though. > > Without INSTALL_DTBS_PRIMITIVE, the current behavior is maintained > (foo1.dtb and foo2.dtb will be installed in this case).
diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst index 9c8d1d046ea5..d803ca5afc07 100644 --- a/Documentation/kbuild/kbuild.rst +++ b/Documentation/kbuild/kbuild.rst @@ -249,6 +249,12 @@ INSTALL_DTBS_PATH specifies where to install device tree blobs for relocations required by build roots. This is not defined in the makefile but the argument can be passed to make if needed. +INSTALL_DTBS_PRIMITIVE +---------------------- +INSTALL_DTBS_PRIMITIVE, if defined, will cause the dtbs_install target to +install the base dtb and overlay dtbo files instead of assembled dtb files +constructed by overlay application. + KBUILD_ABS_SRCTREE -------------------------------------------------- Kbuild uses a relative path to point to the tree when possible. For instance, diff --git a/scripts/Makefile.dtbinst b/scripts/Makefile.dtbinst index 67956f6496a5..14111a86987a 100644 --- a/scripts/Makefile.dtbinst +++ b/scripts/Makefile.dtbinst @@ -22,7 +22,13 @@ quiet_cmd_dtb_install = INSTALL $@ $(dst)/%: $(obj)/% $(call cmd,dtb_install) -dtbs := $(patsubst $(obj)/%,%,$(call read-file, $(obj)/dtbs-list)) +dtbs := $(call read-file, $(obj)/dtbs-list) + +ifdef INSTALL_DTBS_PRIMITIVE +dtbs := $(foreach f, $(dtbs), $(if $(filter %.dtb,$(f)),$(call read-file, $(patsubst %.dtb,%.dtlst,$(f))),$(f))) +endif + +dtbs := $(patsubst $(obj)/%,%,$(dtbs)) ifdef CONFIG_ARCH_WANT_FLAT_DTB_INSTALL
Commit 15d16d6dadf6 ("kbuild: Add generic rule to apply fdtoverlay") introduced the -dtbs syntax to apply overlays during the build process. However, scripts/Makefile.dtbinst is not aware of the -dtbs syntax, so 'make dtbs_install' installs the files directly added to dtb-y. (Presumably, it was intentional.) For example, consider this case: foo1-dtbs := foo_base.dtb foo_overlay1.dtbo foo2-dtbs := foo_base.dtb foo_overlay2.dtbo dtb-y := foo1.dtb foo2.dtb 'make dtbs_install' only installs foo1.dtb and foo2.dtb. It is suitable when the boot image supports a single hardware configuration, or when the boot loader in use does not support applying overlays. However, when creating a boot image with multiple board supports, it wastes storage space, as foo1.dtb and foo2.dtb have foo_base.dtb in common. From a space perspective, a more optimal solution is to install foo_base.dtb, foo_overlay1.dtbo, and foo_overlay2.dtbo, then assemble the final dtb (either foo1.dtb or foo2.dtb) on the boot loader. This commit adds a new flag, INSTALL_DTBS_PRIMITIVE. With INSTALL_DTBS_PRIMITIVE=1, 'make dtbs_install' will install primitive files (such as foo_base.dtb, foo_overlay1.dtbo, and foo_overlay2.dtbo in this case). Without INSTALL_DTBS_PRIMITIVE, the current behavior is maintained (foo1.dtb and foo2.dtb will be installed in this case). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- Documentation/kbuild/kbuild.rst | 6 ++++++ scripts/Makefile.dtbinst | 8 +++++++- 2 files changed, 13 insertions(+), 1 deletion(-)